Furnace regulator system



c. r.:.- VALENTINE FURNACE REGULATOR SYSTEM Jan. 23, 1945.

Filed Dec. 8, 1942 2 Sheets-Sheet 1 INVENTOR N arz'oll E. Vale/227725.

R ww? Y TToRNEY Jan. 23,- 1945.

C. E, VALENTINE FURNAGE REGULATOR-SYSTEM Filed Dem a, 1942 2 sheets-sheet 2 .mvENToR Carra!! E l/alenme.

BY v /Z/ Patented Jan. 23, 1945 UNITED STATES PATENT OFFICE tto 'Westinghouse Electric f& Manufacturing -Company, ,East Pittsburgh, Pa., a corporation sof :Pennsylvania Application December 8, 194.2, `Serial No. 468,235

('Cl. v3111-474) rlhis invention relates to .regulator systems.

and particularly to regulator 'systems fQr gov-- erning .the VVoperation of lthe, movable electrodes in electric furnaces.

In arcfurnaces, the electrodes are disposed to he kraised or lowered in response to predetermined conditions. Usually a motor 'is provided for eflectingthe raising or lowering o'f each electrode, the operation of the motor being controlled 'in response to the current 'Ilowing'through 'the electrode and the potential across the arc. v1n general, such regulator systems are quite satisfactory. However, where such current regulators are usedin conjunction withA a power `sourcehaving .a variable line voltage, then it is ound'that 'the power input 4changes with the Vline, voltage, with the result that the changes Vin power are of vabout twice the magnitude `of the'voltage change. This `phenomenon is "found where the regulator employed operates on the impedance principle ,that there is a constant ratio between'the voltage 'and the current. Although satisfactory for certain applications, in others, such as where it is desiredto maintain a high load factor even though 'the line voltage varies, the known regulatorvsys- 'tems 'are not satisfactory.

It is an object -of this invention to 'provide a v 'furnace yregulator'systemwhich shall -fgovern the *operation of the movable electrodes to maintain a `high load factor,-'a'lthough line voltage varies. Another object .of this invention 4is Ito provide 'a furnace regulator system -so compensated for variations in 'line 4voltage of fthe `power rsource as :to maintain v.a high load 'factor at'the .electrodes :oi the furnace. v

Other objects lof `this invention will `rbecome apparent from the following description when taken in conjunction .with :the :accompanying drawings, inwhich:

Figure l is 4a `diagrammatic IView of a `-furnace regulator Vsystem embodying the `teachings -of [this invention; Yand 2. is a diagrammatic `view 'of another embodiment of @the furnace'regulator system `of vthis invention.

Referring -to the drawings, an electric 4furnace il) is illustrated, the furnace comprising a receptacle 1| 2 containing a Ibath Vof material 1K4 -and .three movable l.electrodes 16., t8 and 52:0. Themovable electrodes I6, I8 and V20 :are directly connected v,to .a three-phase -lsupply circuit comprising line conductors 2h24 and 26 respectively. Eachl yofthe,movable 4elemrodes i6, t8 and 10 :isfdisposed to :be raised tor lowered by `flexible cables 28, 30 Vand'32, respectively, by a motor, a regulator beingprovdedforgoverning the operation of `the motor `in accordance with the current fiowing through the electrode and the potential across the electrode arc. Since each of the regulators oi the embodiment illustrated in Fig. 1 is 'o'f like construction and operates in the vsame manner, it is vbelieved vto be unnecessary to describe more than Vone offth'em. Accordingly, only 'the regulator associated with'the electrode 20 is illustrated in detail and Will-be described,a motor Yand regulator Atherefor Aassociated 'with each of the :electrodes t6 yand i'being 1represented by the blocks y"Hand JIB, respectively.

In Fig. -1,'a motor F34, comprising an Varmature 36 and eld WindingsSB `and 40, is illustrated for raising and'lowering the electrode 20. The arma-` lture :36 'is :mechanically `,connected to the elec-- 'trede '2'0 'in :any suitable manner, ror, as illus'- trated, by means of'the'shaftf'Z which "carries a winding drum '44 vfor receiving :the eXible cable '32.

A regulator 46, which normally 4controls the 4operation 'of the :motor ,34, .comprises Itwo main control electromagnets 48 and :50, which are respectively operated in-.accordance with'the poten tial'across-the arc produced bythe electrode and the current yflowing through the electrode 2t, Aand `two electromagnetic switches r52 and 54 which ,respectively serve to connect the motor across Vthe positive n.and `negative terminals of 'a 'constantpowersource to operateit in a counterclockwise `or :a clockwise direction.

:also pivotally connected to the contact arm The .main control electromagnets 48 and 5l! comprise sectional energizing windings 5B and 5&3, respectively, and ,core armatures 60 and 62respectively. The energizing winding 58 o'f elecw tromagnet ,5.0 is connected `to the conductor- 2% by means of a current transformer E4, the core member of the electromagnetbeing pivotally connected to the contact 'arm `66 A dashpot G8 is connec'tedto the core 62 for re'tarding the speed and magnitude of travel vof the core when violently accelerated beyond normal movement. The energizing winding 56 of electromagnet lf3 is connected from one end through resistors it, "1.2 and 'T4 to lthe conductor 26, and from the other end lthrough conductor Iii to yground `or vthe grounded receptacle 'SITZ containing the bath i4. 'The core member 60 io electromagnet 4.8 'is 5.5

yand iis providedjwith a sdashpo't r1,8.

As illustrated, the contact :arm B6 is pivotally vmounted at ia point .intermediate the points of connection. to the 'core members 60 vand 62 and carries two main contact members 88 and 82 disposed in spaced relation for engagement with the spaced fixed contact members 84 and 8G, respectively, according to the position of the contact arm 65. Springs 88 are connected to the arm 86 and are so disposed as to maintain the arm in a neutral, contact open, position when the electromagnets 48 and 58 are deenergized. The arm 66 and the contact members 88 and 82 are connected to the positive terminal of a constant source of supply (not shown).

The electromagnetic switch 52 comprises a winding 98, which is connected across the posi tive and negative terminals of the constant power source (not shown) when contact members 88 and 84 are engaged, and a core member 92 which operates two contact members 94 and 96. When actuated to a circuit closing position, contact member 84 completes a circuit from the positive termina1 of the constant source of power through the armature 36 and field winding 48 of the motor 34, contact member 94, to the negative terminal to effect a rotation of the motor in a counterclockwise direction to lower the electrode 28 in the furnace. At the same time, contact member 96 closes a circuit to shunt the lower section of the energizing winding of electromagnet 48 and, in effect, decrease the energize.- tion thereof to provide anti-hunting characteristics to the regulator.

The electromagnetic switch 54 is similar to switch 52 and comprises a winding 98, disposed to be connected across the positive and negative terminals of the constant source of power (not shown) when contact members 82 and 86 are engaged, and a core member |88 which operates two contact members |82 and |84. Upon operation of the electromagnetic switch 54, contact member |82 connects the armature 36 and field wind- Anti-hunting characteristics for this operation are provided by the contact member |84, which closes a circuit to shunt the lower section of the energizing winding 58 of electromagnet 58.

The variable resistor 'I4 in circuit with the energizing winding 58 of potential electromagnet 48 is adjusted in accordance with the line voltage. As illustrated. a circuit controlling apparatus |88 of the type disclosed and claimed in Patent No. 2,246,301, issued June 17, 1941, to Hanna et al., and assigned to the assignee of this invention, is utilized for effecting the adjustment of the re sistor 14.

The circuit controlling apparatus I 8B comprises a plurality of leaf springs |88 of conducting material xed at one end thereof and connected to taps along the resistor 14, the free ends of the springs |88 carrying contact members ||8 and being self-biased to the open-,circuit position to seat against a beveled or sloped stop |2. A driver member ||4 of insulating material is disposed to be operated in accordance with the energization of electromagnet ||8 against the bias of a spring ||8 to effect the progressive operation of the leaf spring conducting members |88. glzing winding |28 of electromagnet ||8 is disposed to be energized in accordance with the line voltage, and is connected through the rectifier |22 and by conductors |24 and |26 to line conductors 24 and 26, respectively. A dashpot |21 is@ The ener- I secured to the core of electromagnet I8 to stabilize its operation.

It is to be noted that the motor and regulator represented by the blocks l1 and I9 for the electrodes 8 and I8, respectively, are connected to be energized by a different phase voltage, the current electromagnet winding of the regulator of block l1 being connected to conductor 22 by a current transformer |28, with its adjusting electromagnet for the variable resistor, which is connected in circuit with the potential electromagnet, being connected by conductors |38 and |32 to conductors 22 and 26, respectively. Likewise the current electromagnet of the regulator of block I9 is connected to conductor 24 by the current transformer |34, the adjusting electrcmagnet for adjusting the resistor in circuit with the potential electromagnet being connected by conductors |36 and |38 to conductors 24 and 22, respectively. Thus, each of the motors and the regulators for controlling the operation thereof are connected to be responsive to a particular phase voltage.

In operation, assuming that the system is ener gized and the electrode 28 is positioned for normal operation of the furnace, the kva. load is substantially constant and a normal current flows through the electrode 28, a normal potential existing across the arc from the electrode 28 is the bath I4. Under such conditionsY the electromagnets 48 and 58 are energized to effect a balanced pull on the arm 68,

If for any reason the current flowing through the electrode 28 is decreased below the normal value or the potential across the arc is increased, the energization of the winding 58 of electromagnet 58 is decreased, or the energzation of the winding 58 of electromagnet 48 is increased to effect the engagement of contact members 88 and 84. The engagement of contact members 88 and 84 closes a circuit which extends from the positive terminal of the constant source ofsupply through the contact arm 66, contact members 88 and 84 and the winding 98 of electromagnetic switch 52 to the negative terminal to so energize the switch 52 as to actuate its contact members 94 and 96 to a circuit-.closing position.

When the contact member 94 is in a circuitclosing position, a circuit lis established which extends from the positive terminal of the constant source of power (not shown) through the armature 3B, field winding 48 and the contact member 94 to the negative terminal to sc operate the motor 34 as to effect a rotation of the motor in a counterclockwise direction. A counterclockwise rotation of motor 34 lowers the electrode 28 in the furnace to increase the current flow through the electrode.

At the same time that the contact member 84 of switch 52 closes themotor energizing circuit, contact member 96 also shunts the lower section `of the energizing winding 58 of electromagnet 48 to decrease the energization thereof and tend to separate the contact members 88 and 84. However, because of the dashpot 18, a small time de'. lay is effected lbefore the contact members 88 and 84 are separated. This permits operation of the motor 34 to effect an adjustment in the position of electrode 28 at the same time lproviding anti-hunting characteristics to prevent an over-adjustment.

If power is supplied to the furnace from a source having a variable line voltage, the electromagnet 48 is compensated in accordance with a change in the line voltage to maintain substanti'ally fconstant the 'flood at the'liumace. "Fon'ex- W"ample, if, duringithenormal `oper-ationo'f'thefur- .nacewithithe-electrodeZ infalgivenipositionjthe `:line Avoltage'shouldiincrease, -thenthe'lwinding 112D of electromagnet IIE is so energized asftolactuate 'the driver member IH yin -a direction tofeffect a rprogressive separation o'f L'the :contact members iI I0 toconnect additional lsections of the Iresistor `iT4 in circuit with :the venergizing winding f56 of .electromagnet S48, and thereby, linfeiectyto so dekcresse the .energization of the .lelectromagnet f as ito unbalance the ymagnetic pulhof .the electroy:magnets 48 y'and :'50 on the icontact Iarm :66. Un- Jder such conditions, the ycontact :member 82 is actuated :into engagement lwith contact member 86 toclose a circuitwhich.extends'from th'e positivefterminalrof the source of :power .'(not shown) through the contactarm 66, contactl members :82 andi86, the energizing minding 9B :of Ithe -switch #.54 ftolthe negative terminallof the constant source -fof power ,to operate Ithe electromagnetic .switch i518 1V:toits :circuit L-closing position.

'When :thus energized, `the contact member .-I`02 .of ith-e :switch 15.4 connects ithe .armature .36 and field xwinding '88 of 'motor .3"4 across the positive and :negative terminals `fof fthe constant 'source Iof :power =6not shown) to :operate 'the `motor in .sa .clockwise direction, and Ythereby :raise the .eleclvtrede -20 fand, in effect, decrease the `current flow rthroughitheelectrode. fior ian increase in the line evolta-ge, lthe electrode 220 tisfso .positioned .res torsubstantially-maintainfthe kva. co.nstant.

Dmlingitheiforegding Operation it nis, of icourse, itc lre'notcd 1that ithe .Contact :member il 04 of Ethe yswitch 54 is also actuated tozaciirouit-.closi'ng position to reffect shunting nf the ilower section of decrease :the energization 'thereof and 'tend -to separate rthe contact e-members 1t82 yand r8.6. Howfeuer, lthe 'fdashpot168 yfunctions :to :prevent Yimme- `diate separation -of Vthe `:contact vmembers 8.2 and :86, .thereby ,permitting an ,operation .of ithe motor .34 te Aeffect -an Aadjustment in the fposition -of the electrode 20.

lf., during the xnormal 4operation yof :the regu- ,latcr 46 to effect al1-adjustment in rthe -position of the electrodelli, that is, where the current Vvilovv ithrough Vthe electrode 2.0 is :decreased :rorn the ,normal I,current :,-and lthe .potential across Ithe farcis increased so as to eiiect-an .operationof ,the .contact Yarm :66 to effect .a lclosing `of .the contact .members 80 and i.813 .toeoperate'the ,frnotor' inra countercloclswise direction, as described herein- ,before the line voltage should vary, :as-described, v.then the increase inthe .line l.voltagewould -elect .an .dpe'ration of the y.adjusting electromagnet II G "to connect additional sections .of Vthe yresister "ld in .circuit with .the potential ,electromagnet ,4,8 to tend to `decrease .the `energization thereof to interrupt the operation .of ythe motor 134. lf such 'change iin ,the Iline .voltage is sufficiently great, `then the electromagnet 48 is So deenergized-.as -to eiiect .the .separation .of the contact members 80 andli and an engagement of thev contact members 82 and 86 to thereby operate the motor 34 in a clockwise direction to raise the electrode, as described hereinbefore. Thus the change in line voltage is cumulative with any change in normal operating conditions of the furnace vfor controlling the position of the electrode 20 to maintain a substantially constant kva. In the embodiment illustrated in Fig. 1, each of the electrodes I6, I8 and 20 are positioned in response to a change in the particular phase voltage, the operation of the regulator associated with one of the elec.

tif

'ftrodes being :substantially independent of the operation :o'f the regulator associated fwith thenther electrodes.

In the embodiment .of the invention illustrated 1in Fig. i2, :each of #the electrodes I6, .I.81andi20-is positioned in response .to lthe Ioperation of amotor land regulator .therefor similar totheembodiment illustrated in Fig. l1. However, the energizing winding 'I-Zll ci' 4.the adjusting electromagnet .I t6 ziorfcontrollingithe 'connection ofthe resistor '1Min `circuit with the lpotential electromagnet `48 is connected iniseries icircuit relation with .the energizing winding M0 of an adjusting electromagnet I42 of the block I.9 and the energizing winding IMI of .adjusting electromagnet |46 ofthe Y.block IFI, so 1thatreachiof `the Vadjusting electro- `magnets `is `energized ysimultaneously `With .a change in Vthe Aline voltage. yills illustrated, the series-connected :energizing windings ofthe electromagnets 'I;I6, 'M2 and |46 :are connected 'by conductors M8 .and |50 :to the terminals of va three-phase rectifier 152, which .is connected to fthe iline conductors 2-2, 24 Aand `2li. The electro- -`i'nagnets :i I6, lM2 and M6 lare so constructed lthat the iinductancerof the energizing windings'effectively smooths any 'ripple of vthe rectified current which :flows .through their energizing windings.

Inthis embodiment, the regulator and motor `associatedwith each of the .electrodes I6, fit-.and .2D function in the `same manner .as the regulator and motor describe-d hereinbefore with respect to the -.-positioning of electrode 2.0 of L'the1embodiment `illustrated in Fis. i, with the exception that-.the

.zpotential .electromagnets .of .each of -Athe regulaitors :are simultaneously 'compensated Ifor any Vchange in the average voltage .of fthe :polyphase Vvoltage source of supply 'to :the electrodes.

.sistor .'Idyconn'ected in circuit With the energizing winding i56 eiects` anioperation of the regulator xl'in'exac'tly thesame'manner as the same change affected :the operation ofthe regulator 46 in the regulating system shown lin Fig. 1. In other Words fupon a change in the polyphase voltage,

Asuch `:asan increase, Leach of the electromagnets vtherellary 'maintain "substantially `constant kva. re-

gardless :nfA the :increase iin the polyphase voltage ci the :power source.

\By`:means of this invention, 'a more Asensitive .control of the 1positioning of the electrodes of the furnace and a more sensitive regulation of the operation of the electrode motor is obtained. Further, it is possible to maintain substantially constant kva., making it possible to more Widely utilize the furnaces of the type referred to.

Although this invention has been described With reference to particular embodiment thereof, it is, of course, not tobe limited thereto except in so far as is necessitated by the scope of the appended claims.

I claim as my invention:

1. In an arc furnace regulator system, a source of power supply having a variable line voltage, a movable electrode, means disposed for raising and lowering the electrode, a regulator comprising a current electromagnet energized in accordance with the current flowing through the electrode and a potential electromagnet energized in accordance with the potential across the electrode are for operating the raising and lowering means, an adjustable resistor connected in circuit relation with the potential electromagnet, and means responsive to a change in the line voltage to adjust the resistor and vary the energization of the potential electromagnet in accordance with the change in the line voltage.

2. In an arc furnace regulator system, in combination, a source of power supply having la variable line voltage, a movable electrode, a motor disposed for raising and lowering the electrode, a, regulator comprising a current electromagnet energized in accordance with the current fiowing through the electrode and a potential electromagnet energized in accordance with the potential across the electrode arc for operating the motor, means connected in circuit relation with the potential electromagnet disposed to be ioperated to change the energization of the electromagnet, and means responsive to a change in the line voltage disposed to operate said iirst'merans to effect a change in the energization of the potential electromagnet in accordance with the change in the line voltage.

3. In an arc furnace regulator system, in mbination, a source of power supply having a variable line voltage, a movable electrode, a motor disposed for raising and lowering the electrode, I

a. regulator comprising a current electromagnet energized in accordance with the current flowing through the electrode and a potential electromagl'lel energized in accordance with the potential across the electrode arc for operating the motor, a sectionalized resistor connected in circuit relation with the potential electromagnet, a plurality of swiches disposed to be operated to control the connecting of the resistor sections in circuit with the potential electromagnet, and an electromagnet responsive to a change in the line voltage disposed to operate the switches to effect a change in the energization of the potential electromagnet in accordance with the change in the line voltage. 4. In an arc furnace regulator system, in comblnation,I a source of power supply having a variable line voltage, a movable electrode, a motor disposed for raising and lowering the electrode, a regulator comprising a current electromagnet energized in accordance with the current flowing through the electrode and a potential electromagnet energized in accordance with the potential across the electrode arc for operating the motor, a sectionalized resistor connected in circuit relation with the potential electromagnet, a plurality of switches disposed to be operated to control the connecting of the resistor sections in circuit with the potential electromagnet, and means comprising a rectifier and an electromagnet connected in circuit with the power supply disposed to operate the switchesl to effect a change in the energization of the potential electromagnet as the line voltage changes.

5. In an arc furnace regulator system, in com bination, a three-phase source of power supply having a variable voltage, a plurality of movable electrodes, a motor associated with each of the electrodes disposed for raising and lowering the associated electrode, a regulator associated 'with each' motor, each of the regulators comprising a current electromagnet energized in accordance with the current flowing through an associated electrode and a potential electromagnet energized in accordance with the potential across the arc of the associated electrode for operating the mo tor associated therewith, an adjustable resistor connected in circuit relation with the potential electromagnet of each of the regulators, means including an electromagnet having an energizing winding associated with each of the resistors disposed for adjusting the associated resistor, the energizing windings of the adjusting electromagnets being connected in series circuit with each other, and a three-phase rectifier connected in circuit between the' energizing windings of the adjusting electromagnets and the power` supply to provide a rectied current for energizing the adjusting electromagnets in accordance with the variable line voltage of the power supply, the adiusting electromagnets thereby controlling the energization of the potential electromagnet of each of the regulators in accordance with the variable line voltage.

6. In an arc furnace regulator system, in combination, a three-phase source of power supply having a variable voltage, a plurality of movable electrodes, a motor associated with each of the electrodes disposed for raising and lowering the associated electrode, a regulator associated with each motor, each of the regulators comprising a current electromagnet energized in accordance with the current flowing through an associated electrode and a potential electromagnet energized in accordance with the potential across the arc of the associated electrode for operating the motor associated therewith, means connected in circuit relation with each of the potential electromagnets for controlling the energization thereof in accordance with the variable line voltage of the power supply, said means being connected in series circuit relation with each other to simultaneously effect a change in the energization of the potential electromagnet associated therewith, and means connected in circuit between the series connected controlling means and the power source to provide a unidirectionalfcurrent for simultaneously operating the controlling means of each of the potential electromagnets 1n accordance with the variable line voltage of the power supply.

CARROLL E. VALENTINE. 

